exercism-php/roman-numerals/RomanNumerals.php

<?php

/*
 * By adding type hints and enabling strict type checking, code can become
 * easier to read, self-documenting and reduce the number of potential bugs.
 * By default, type declarations are non-strict, which means they will attempt
 * to change the original type to match the type specified by the
 * type-declaration.
 *
 * In other words, if you pass a string to a function requiring a float,
 * it will attempt to convert the string value to a float.
 *
 * To enable strict mode, a single declare directive must be placed at the top
 * of the file.
 * This means that the strictness of typing is configured on a per-file basis.
 * This directive not only affects the type declarations of parameters, but also
 * a function's return type.
 *
 * For more info review the Concept on strict type checking in the PHP track
 * <link>.
 *
 * To disable strict typing, comment out the directive below.
 */

declare(strict_types=1);

class mapping
{
    public int $n;
    public string $lit;

    public function __construct(int $n, string $lit)
    {
        $this->n = $n;
        $this->lit = $lit;
    }
}

function toRoman(int $number): string
{
    $literals = [
        new mapping(10_00, "M"),
        new mapping(9_00, "CM"),
        new mapping(5_00, "D"),
        new mapping(4_00, "CD"),
        new mapping(1_00, "C"),
        new mapping(90, "XC"),
        new mapping(50, "L"),
        new mapping(40, "XL"),
        new mapping(10, "X"),
        new mapping(9, "IX"),
        new mapping(5, "V"),
        new mapping(4, "IV"),
        new mapping(1, "I"),
    ];
    $roman = "";
    foreach ($literals as $mapping) {
        while ($number >= $mapping->n) {
            $roman .= $mapping->lit;
            $number -= $mapping->n;
        }
    }
    return $roman;
}